What methods are there to level your particle hair?
Mainly, you have a non default parameter here : the brownian (agitation) field set to a value. Set it back to 0 to have a regular aspect.

After that, as you want to have a short hair (like brush), you may lower the segments (as their are used for the hair movement, mainly for long hair).

And to have more density, simply grow the amount of emitted particles.



As some faces are not visible, you should also use a vertex group to locate the hair where you want on the visible faces : in consequence, the visible faces will have more hair on them with the same or lower overall hair amount.